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#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <sys/stat.h>
#include <limits.h>
#include <sys/resource.h>
#include <syslog.h>
volatile int init = 0;
void restart(int sig) {
if(init) {
closelog();
printf("restart\n");
}
openlog("meow", LOG_CONS|LOG_NDELAY|LOG_PID, LOG_USER);
init = 1;
}
#define min(x, y) ((x) < (y) ? (x) : (y))
#define CHECK_WITH_RET(x, ret, format, ...) \
do { \
if(!(x)) { \
fprintf(stderr, format, __VA_ARGS__); \
ret \
} \
} while(0)
#define CHECK(x) CHECK_WITH_RET(x, return -1;, "%s:%d\nerror: %s\nunmet condition:\"%s\"\n", __FILE__, __LINE__,strerror(errno), #x)
#define CONDITION(x) CHECK_WITH_RET(x, exit(2);, "%s:%d\nunmet condition:\"%s\"\n", __FILE__, __LINE__, #x)
#define CHECKMAIN(x) CHECK_WITH_RET(x, exit(1);, "%s:%d\nerror: %s\nunmet condition:\"%s\"\n", __FILE__, __LINE__,strerror(errno), #x)
int makeDaemon() {
pid_t pid;
switch ((pid = fork())) {
case -1:
CHECK(0);
case 0:
break;
default:
printf("pid:%ld\n", (long)pid);
_exit(0);
}
CHECK(setsid() != -1);
CHECK(umask(0) != -1);
CHECK(chroot("/") != -1);
int nullfd = open("/dev/null", O_RDWR);
CHECK(nullfd != -1);
CHECK(dup2(nullfd, STDIN_FILENO) != -1);
CHECK(dup2(nullfd, STDOUT_FILENO) != -1);
CHECK(dup2(nullfd, STDERR_FILENO) != -1);
CHECK(close(nullfd) != -1);
long fdmax = sysconf(_SC_OPEN_MAX);
struct rlimit rlimit;
CHECK(getrlimit(RLIMIT_NOFILE, &rlimit) != -1);
for(int fdi = 0; fdi < min(fdmax, rlimit.rlim_cur); fdi++) {
close(fdi);
}
CHECK(signal(SIGHUP, restart) != SIG_ERR);
return 0;
}
struct logmesg {
int level;
char *str;
};
int main(int argc, char **argv) {
printf("pid:%ld\n", (long)getpid());
CHECKMAIN(makeDaemon() != -1);
printf("pid:%ld\n", (long)getpid());
restart(SIGHUP);
CHECKMAIN(signal(SIGHUP, restart) != SIG_ERR);
CONDITION(argc >= 3);
struct logmesg *data = malloc(sizeof(struct logmesg));
data->level = atoi(argv[1]);
CONDITION(data->level >= 0 && data->level <= 7);
int strlen = 0;
for(char **argvi = &argv[2]; *argvi; argvi++) {
strlen += snprintf(NULL, 0, "%s %s", (char *)NULL, *argvi);
}
char *str = malloc(strlen + 1);
for(char **argvi = &argv[2]; *argvi; argvi++) {
strlen += sprintf(str, "%s %s",str, *argvi);
}
data->str = str+1;
syslog(data->level, "%s", data->str);
printf("syslog: %s\n", data->str);
closelog();
}
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